Handheld 3D Printer Delivers Skin-Precursor Sheets Directly to Full-Thickness Burns

By Will Boggs MD

February 05, 2020

NEW YORK (Reuters Health) - A new handheld 3D printer can be used to deliver skin-precursor sheets directly to wound beds and improve healing in full-thickness burns, according to a preclinical study in a porcine model.

"The ability to consistently deliver (human) cells in a matrix and onto practically relevant wound surfaces, i.e., of arbitrary size and topology, has been a significant limitation that we believe has been overcome with our handheld instrument," Dr. Alex Guenther of the University of Toronto, in Canada, told Reuters Health by email.

Large burn areas often leave insufficient healthy skin to use as autologous skin grafts. Acellular biodegradable scaffolds have been used as alternatives, and different cellular approaches using patient-derived autologous or donor-derived allogeneic cells are under development.

Dr. Guenther and colleagues developed a handheld 3D bioprinter designed to deliver a fibrinogen-based bioink containing mesenchymal stromal cells directly onto burn-wound surfaces of arbitrary size, shape and topography.

A burn area of 2,000 cm2 (similar to an average burn area of the human posterior trunk or about 10% of total body surface) would require about 40 mL of biomaterial with 40 million cells in total, with a deposition time of 70 minutes, the researchers report in Biofabrication.

The time required to cover a full-thickness burn wound size of 5x5 cm took an average of 0.89 min, using 480 uL of biomaterials with a total of 480,000 cells.

The researchers treated full-thickness burn wounds on four porcine models using the handheld instrument and found that the wounds were uniformly covered with the deposited material immediately after delivery.

After 28 days, the treated wounds showed superior healing profiles with a reduction in inflammation, scarring, and contraction, compared with untreated burns and burns treated with acellular materials.

Histologically, treated wounds showed epidermal cell repopulation in normal ranges, whereas burn controls and acellular treatments showed regions with poor cell repopulation in addition to localized areas with hyperplasia or hypoplasia.

"Cell delivery of bioprinting should in many clinical cases probably not be done with a printer that is scaled to patient dimensions," Dr. Guenther said. "That would make for a very bulky instrument. In contrast, we believe the demonstrated handheld device is advantageous. Also, because its form is similar to another handheld instrument routinely used by burn surgeons for many decades: a dermatome."

Co-author Dr. Marc G. Jeschke of Sunnybrook Health Sciences Centre, also in Toronto, told Reuters Health by email, "This could change the way we practice for burn patients and patients with large wounds as we could restore a patients skin with no scar, no pain as we avoid donor sites and a significantly shortened hospital stay from months to weeks."

"We have not shown that printing can restore autologous skin of a patient yet," he said. "The issue at this time is showing efficacy, but this is being studied."

The researchers report no conflicts of interest. SOURCE: https://bit.ly/2H4UsQZ Biofabrication, online February 4, 2020